The design

From a graphic design standpoint, only four elements needed to be created: the backdrop, the aliens, the animated missiles, and a single-frame opening screen (a fifth element, the missile launcher, was kept as a simple block icon). For these, Dekel turned to friends Ben Barnett and Alex Orelle.

At first only one alien was designed, the somewhat more sinister green one, dubbed Dodo. But when it was clear that the project called for more visual variety, a second, unnamed alien was quickly whipped up: Barnett and Orelle opened up a copy of the three images representing Dodo in Adobe Photoshop and then changed most of the green to red. A new set of eyes were layered over (creating a slightly more comical effect), and the result was, like the original, imported as 8-bit dithered artwork. To further differentiate the two aliens, the artwork for each was imported into Cast slots in a slightly different order. As the animation scripts cycled through their images, this had the effect of making each seem to move in a distinctive pattern, although the difference is more in sequence than in style.